1. Field of the Invention
The present invention relates to a mold clamping system of an injection molding machine or the like, more particularly relates to a mold clamping system which uses mold opening and closing mechanisms to move a movable platen toward a fixed platen, engages half nuts with engagement parts formed at tie bars, then uses clamping cylinders to pull the tie bars and clamp the mold.
2. Description of the Related Art
In the past, as mold clamping systems which use mold opening and closing mechanisms to move a movable platen toward a fixed platen, engage half nuts with engagement parts formed at tie bars, and use clamping cylinders to pull the tie bars and clamp the mold, the ones described in Japanese Patent Publication (A) No. 8-276482, Japanese Patent Publication (A) No. 2003-340827, and Japanese Patent Publication (A) No. 2005-53022 (U.S. Pat. No. 7,179,409) have been known. In these mold clamping systems, it is necessary to adjust the positions of the tie bars in order to engage the half nuts with the engagement parts of the tie bars. Mechanisms are provided for that.
In Japanese Patent Publication (A) No. 8-276482, as shown in FIG. 1, sub cylinders for adjusting the positions of the tie bars are attached to rams of clamping hydraulic cylinders. However, the mechanism of Japanese Patent Publication (A) No. 8-276482 has the problem that the overall length of the mold clamping system becomes long. Further, as a system for solving problem of Japanese Patent Publication (A) No. 8-276482, there is the one described in Japanese Patent Publication (A) No. 2003-340827. In Japanese Patent Publication (A) No. 2003-340827, actuators are provided on the insides of the clamping cylinders. The actuators are connected to the clamping cylinders through link mechanisms and position adjustment rods. However, in Japanese Patent Publication (A) No. 2003-340827, the link mechanisms etc. are complicated. This leads to a cost increase. Further, in Japanese Patent Publication (A) No. 2005-53022 (U.S. Pat. No. 7,179,409), a servomotor mechanism, first cylinder, and second cylinder are separately necessary, so the structure is complicated. This leads to a cost increase.